Drop a bit of dead code

The `cache_key` argument to `ConnectionSettings` is unused.

Author: elprans

asyncpg/protocol/codecs/base.pyx

@@ -483,7 +483,7 @@ cdef uint32_t pylong_as_oid(val) except? 0xFFFFFFFFl:
 
 
 cdef class DataCodecConfig:
-    def __init__(self, cache_key):
+    def __init__(self):
         # Codec instance cache for derived types:
         # composites, arrays, ranges, domains and their combinations.
         self._derived_type_codecs = {}

asyncpg/protocol/protocol.pyi

@@ -222,7 +222,7 @@ class Codec:
 
 class DataCodecConfig:
     __pyx_vtable__: Any
-    def __init__(self, cache_key: object) -> None: ...
+    def __init__(self) -> None: ...
     def add_python_codec(
         self,
         typeoid: int,

asyncpg/protocol/settings.pyx

@@ -11,12 +11,12 @@ from asyncpg import exceptions
 @cython.final
 cdef class ConnectionSettings(pgproto.CodecContext):
 
-    def __cinit__(self, conn_key):
+    def __cinit__(self):
         self._encoding = 'utf-8'
         self._is_utf8 = True
         self._settings = {}
         self._codec = codecs.lookup('utf-8')
-        self._data_codecs = DataCodecConfig(conn_key)
+        self._data_codecs = DataCodecConfig()
 
     cdef add_setting(self, str name, str val):
         self._settings[name] = val